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SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint (SQL  
  : alter table `blagst_questions_tags_relationships` add constraint `questio  
  ns_tags_relationships_question_id_foreign` foreign key (`question_id`) refe  
  rences `blagst_questions` (`id`))   

Schema::create('questions_tags_relationships', function (Blueprint $table) {
            $table->integer('question_id')->index();
            $table->integer('tag_id')->index();
        });

        Schema::table('questions_tags_relationships', function ($table) {
            $table->foreign('question_id')->references('id')->on('questions');
            $table->foreign('tag_id')->references('id')->on('tags');
        });

Schema::create('questions', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('question_author')->unsigned();
            $table->string('question_title')->index();
            $table->text('question_details');
            $table->string('question_status')->default('Ожидает подтверждения');
            $table->timestamp('question_created');
            $table->timestamps();
        });

        Schema::table('questions', function ($table) {
            $table->foreign('question_author')->references('id')->on('users');
        });

Schema::create('tags', function (Blueprint $table) {
            $table->increments('id');
            $table->string('tag_name');
            $table->string('tag_name_eng');
            $table->string('tag_description');
            $table->timestamp('question_created');
            $table->timestamps();
        });

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NotFoundHttpException in RouteCollection.php line 161:
in RouteCollection.php line 161
at RouteCollection->match(object(Request)) in Router.php line 821
at Router->findRoute(object(Request)) in Router.php line 691
at Router->dispatchToRoute(object(Request)) in Router.php line 675
at Router->dispatch(object(Request)) in Kernel.php line 246
at Kernel->Illuminate\Foundation\Http\{closure}(object(Request))
at call_user_func(object(Closure), object(Request)) in Pipeline.php line 52
at Pipeline->Illuminate\Routing\{closure}(object(Request)) in CheckForMaintenanceMode.php line 44
at CheckForMaintenanceMode->handle(object(Request), object(Closure))
at call_user_func_array(array(object(CheckForMaintenanceMode), 'handle'), array(object(Request), object(Closure))) in Pipeline.php line 136
at Pipeline->Illuminate\Pipeline\{closure}(object(Request))
at call_user_func(object(Closure), object(Request)) in Pipeline.php line 32
at Pipeline->Illuminate\Routing\{closure}(object(Request))
at call_user_func(object(Closure), object(Request)) in Pipeline.php line 103
at Pipeline->then(object(Closure)) in Kernel.php line 132
at Kernel->sendRequestThroughRouter(object(Request)) in Kernel.php line 99
at Kernel->handle(object(Request)) in index.php line 54

Route::get('blade', function () {
    return view('welcome');
});